This invention relates to a mobile communication system in which a communicating party is authenticated when communication is performed between a mobile terminal and a device on the side of a network, and to an apparatus constituting this system. More particularly, the invention relates to a mobile communication system in which, when a signal requesting execution of a prescribed operation is received from a device on the side of a network, whether the device on the network side is an authorized device is authenticated at a mobile terminal, and to an apparatus constituting this system.
Various authentication methods in mobile communication systems have been proposed. For example, Japanese Patent Application Laid-Open No. 10-336744 discloses an authentication technique whereby the validity of a mobile station that has attempted to place a call is authenticated on the side of the base station. According to this prior art, (A) when a call starts to be originated from a mobile station to a base station, (B) the base-station side transmits to the mobile station a first random number that specifies one code key number among a plurality (N-number) of shared code key numbers. (C) From the first random number received the base-station side, the mobile station identifies one code key number from among a plurality (N-number) of code key numbers and sends the base-station side a second random number representing this code key number. (D) The base-station side compares the code key number identified by the second random number transmitted from the mobile-station side and the code key number specified by the first random number, and the base station verifies that the mobile station that attempted to originate the call is authentic only if the two code key numbers match.
Further, an authentication technique for checking the authenticity of a base station on the side of a mobile station has been disclosed in the specification of U.S. Pat. No. 5,282,250 (Jan. 25, 1994). If a large number of corresponding relationships between a random number issued by an authorized base station at the time of authentication in response to an originated call and results of an authentication operation with which mobile stations respond to this random number are accumulated and copied to an unauthorized terminal, it will be possible to make a telephone call using this unauthorized terminal without being billed. Hence a malicious base station may perform a false authentication operation in order to acquire these corresponding relationships unjustly. The above-cited U.S. Pat. No. is a technique whereby the authenticity of a base station is checked on the side of the mobile station in order to prevent a false authentication operation from being carried out by a malicious base station.
Further, the specification of Japanese Patent Application Laid-Open No. 10-42362 discloses a technique whereby transmission of radio waves from a mobile station is halted in accordance with a request signal from the network side in order to prevent medical equipment and other devices from being adversely affected by emission of radio waves in a hospital or the like. FIG. 14 illustrates an example of prior art in a case where a base station requests the halting of radio-wave emissions from a mobile station. When a mobile station 1 receives a signal (request signal C), which requests the halting of radio-wave transmission, from a base station (not shown), a controller 1b recognizes receipt of the request signal through a receiver (RX) 1a. In response, the controller 1b issues a switch (SW) 1c an OFF signal in order to halt transmission. In response to the OFF signal, the switch 1c stops a transmit signal, which is produced by a transmitter (TX) 1d, from entering an antenna ATN. Thus, when requested by the base station, the mobile station 1 halts the emission of radio waves regardless of user intentions.
The halting of radio-wave emissions from a mobile station or the provision of internal information of a mobile station based upon a request on the side of the base station regardless of user intentions does not pose a problem so long as the requesting base station is an authorized base station based upon an agreement with the user. If the requesting base station is a malicious base station, however, this does pose a problem because there is the danger that implementation of communication will be obstructed wrongfully or that terminal information concerning the mobile station or personal information set by the user will be used secretly.